1. Field of the Invention
This invention relates to the use of gums as adjuvants in ophthalmic compositions to potentiate the miotic response to cholinergic agents, particularly echothiophate iodide which is used in treatment of glaucoma; this allows the administration of lower, more effective dosages of said cholinergic agents, thereby alleviating side effects. In a further aspect, this invention relates to a drug delivery system which is a gel and is useful for topical application.
In this application the term "adjuvant" is defined as found in Stedman Medical Dictionary, 22nd Edition as "that which aids or assists; denoting a remedy that is added to a prescription to assist or increase the action of the main ingredient".
2. Description of the Prior Art
The prior art discloses a variety of gums and polymers used as adjuvants in ophthalmic compositions.
For example, C. Rosenblum et. al. in Arch Ophthal, 77:234-237, 1967, disclosed the use of hydroxyethyl cellulose to increase the systemic absorption by ocular tissues of dexamethasone. With drugs such as erythromycin propionate and sulfapyridazine sodium, Y. F. Maichuk, Am. J. Ophthal, 74:694, 1972 taught the use of polyvinyl alcohol to potentiate their pharmacological response. Similarly, guar gum was found to increase the corneal absorption of tropicamide as reported by Lee et al, J. Pharm. Sci. 63:721, 1974.
The use of gum and polymer combinations is also disclosed, such as their application as a bactericidal cleanser, lubricant, and wetting agent. German Pat. No. 2,051,369 is illustrative, wherein is disclosed a solution containing polyethylene glycol, poly(ethyleneoxide), and an ophthalmic medicine. British Pat. No. 1,337,105 teaches a different combination of polymers for use in eye wash solution containing hydroxyethyl cellulose and polyvinyl alcohol. Still another example is presented by British Pat. No 1,340,518 which discloses ophthalmic compositions containing an ophthalmic medicament, a polyalkylene glycol, a cellulosic derivative or mixture of such derivatives, and, optionally, polyvinyl pyrrolidone. See also U.S. Pat. Nos. 3,944,427 and 3,700,451 which disclose gelable and gelled compositions containing agar, xanthan gum, and locust bean gum in a liquid medium for use as a carrier of therapeutic solutions, but particularly as a carrier for photo-processing solutions. These compositions, however, are rigid gels at room temperature.